Trichomonas vaginalis is the cause one of the most widespread sexually transmitted diseases in the world. The main pathological manifestations of a trichomonad infection in women are abdominal pain, itching, and presence of a foul-smelling discharge with abundant leukocytes Honigberg, B. M. 1978. Trichomonads of importance in human medicine, p. 275. In J. P. Kreier (ed.), Parasitic protozoa, vol. II. Academic Press, Inc., New York, N.Y. In men, the infection is mostly asymptomatic, although it can sometimes lead to urethritis, prostatitis, and epididymitis. Krieger, J. N. 1981. Urologic aspects of trichomoniasis. Investig. Urol. 18:411-417. The infection recently has been associated with severe complications, including infertility. Moskowitz, M. O., and B. C. Mellinger. 1992. Sexually transmitted diseases and their relation to male infertility. Urol. Clin. North Am. 19:35-45. Trichomonas infection also gives rise to an enhanced predisposition to neoplastic transformation in cervical tissues, and progression of human immunodeficiency virus. Zhang, Z. F., and C. B. Begg. 1994. Is Trichomonas vaginalis a cause of cervical neoplasia? Results from a combined analysis of 24 studies. Int. J. Epidemiol. 23:682-690; Laga, M., A. Manoka, M. Kivuvu, B. Malele, M. Tuliza, N. Nzila, J. Goeman, F. Behets, V. Batter, M. Alary, W. L. Heyward, R. W. Ryder, and P. Piot. 1993. Non-ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study. AIDS 7:95-102; Wasserheit, J. N. 1992. Interrelationship between human immunodeficiency virus infection and other sexually transmitted diseases. Sex. Transm. Dis. 19:61-77.
T. vaginalis can survive and flourish in a hostile changing environment. Its ability to evade the host immune system is an important aspect of its pathogenesis. Avoidance of complement is a strategic tactic which is used by T. vaginalis to overcome the human immune system. It is known that T. vaginalis activates an alternative pathway of complement but workers are only just beginning to understand how the parasite does this and how it escapes eradication. It is known that T. vaginalis takes advantage of a niche in which little complement is present. Cervical mucus is surprisingly deficient in complement. Menstrual blood represents the only source of complement available to the vagina. Interestingly, its complement activity is about half that of venous blood, and about one-third of menstrual blood samples have no complement activity at all. Menstrual blood has appreciable complement-mediated cytotoxicity toward T. vaginalis, and although a reduction in parasite concentration is seen during menses, trichomonal infection persists even after menses. While the number of organisms in the vagina actually decreases during menses, virulence factors, many of which are mediated by iron, contribute to the exacerbation of symptoms at this time.
Iron is a contributing factor in complement resistance by T. vaginalis. It appears that iron up-regulates the expression of CPs, which have been found to degrade the C3 portion of complement on the surface of the organism and that this mechanism allows the organism to evade complement-mediated destruction. Alderete, J. F., D. Provenzano, and W. Lehker. 1995. Iron mediates Trichomonas vaginalis resistance to complement lysis. Microb. Pathog. 19:93-103.
Current methods for detecting and diagnosing Trichomonas infection involve a trip to a clinic or doctor's office. However, given the prevalence of Trichomonas infections and their potential harm, faster, simpler methods for detecting Trichomonas infections are needed. In particular, a diagnostic device is needed that can be used outside of a clinical setting, for example, in the home or in the field.